Lifting-jack.



A. VAN FLEET.

LIFTING JACK.

4 APPLIOATION mum 11111.3, 1011.

Patented M131, 1912.

v 1 1 1 u a 1 1 1 M H; lllllllll. 1|. 0" N 7. M f f 5 UNITED STATES PATENT OFFICE. v

ALFRED VAN FLEET, or 30mm, rumors, ASSIGNOR T WILLIAM E. r'na'rr, or

- I cnrcaao, rumors. v

LIETING-JACK.

Specification of Letters Patent.

Application filed March 8,1811. Serial 1%. 612,137.

- To all w iio'm it may] concern:

' ful Improvements in Lifting-J acks, of which the following is a specification.

The main object of this invention is to providean improved and simple formof lifting jack, of the pawl and rack type, having improved means for controlling the ac tion of the parts so that the rack may be raised or lowered by similar movements of the operating lever;

An illustrative embodiment of this invention-is shown in the accompanyingdrawings, in which I Y 3 Figure 1 is a side elevation, partly sectional, of alifting jack constructed accord? ing to this invention, and illustrating the.

relative positions of the rack and .pawls when the device is to. be operated to ra1s e a load. Fig. 2 is a similar View, illustrating the. relative positions of the rack and pawls,

when the device is to beoperated for lower:- ing the load, the lever being shown in its lowermostposition, so as to illustrate the manner 'in whichthe upperpawl is urged into engagement with the rack. Fig. 3 is a view similar to that shown in Fig. 2, the lever being shown in its uppermost position, so asto illustrate the manner in which the lowerpawlis urged into engagement-with the rack. Fig. .4 is a transverse sectional detail of the device taken on .the. line A-A of Fig.1; I a v In the construction-shown in the drawings, the'ilifting jack comprises a standard or frame 1, which is preferably a single casting, in which is slidably mounted a lifting member 2, havingon its rear face a rack 3.; A lever 4 is ful'crumed at 5 to the standard 1, and isladapted tohave secured thereto a handle 6,'by means of which the raising and lowering'of the member 2 is accomplished.

' A-holding pawl 7 is pivotally mounted at '8 infthe lowerpart of t e standard 1 in position to engagelwi'th the rack 3.. A second or lifting 'pawl 9,is pivotedyait 10 to the-lever 1 and also adapted to engage the'raek 3.

The pawls 7' and 9 are connected together.

by a rod orlink 11.so that their normal movements, as influenced byth'e spring 12,

will be substantially identical, the md'llf bo ing pivotally connected to the lower endof rod 11 and permit it to move relatively thereto. This spring. is arranged so that it normally exerts a pull'on thejrod. 11 at a point between the pawls and thereby urges both pawls 7 and 9 into engagement with the rack 3. The action of the spring 'is con trolled by a cam shaped member 14 which Patented Dec. 31,1912.

' 'an'gles thereto and apertured to receive the I may be shifted so that the pressure of" the."

spring will be directed to normally urge both pawls into or out of engagement ac cording to the position of the member 14. 3 v

its normal position. When the member-14 is rotated on its axis a half revolution, its high surface or shoulder 16 will engage and urge the spring 12 forward, so as'to exert a .ielding pressure on ,the rod 11 and effect t e retraction of the pawls 7 and 9. The member 14 is operated by a crank 17, secured thereto outside of the .frame.- Stops 18; and 19 are positioned on the-frame 1 to limit the move-' ment of the crank 17 which is held in either limiting position by the pressure of -"the spring12 -on the cam.

A lug or-shoulder 20 ner face of'the frame 1, near'its 11 'per end. When the spring12 Urges-the paw s toward is formed on the in 'end' of the-pawl 9 abuts against the shoulder 20, whereupon thepawl is guided intoeni gagement with the rack 3. The lever 4 extends 'beyond'the pivot of the pawl9. so as .to form a cam surfaoe'21, which, engages the tapered u per ,en'd of the pawl 7 whenthe' lever-ban le'is given an-upward stroke and urges said pawl 7 into engagement with the; rack 3. As the spring 12 urges the pawls toward their retracted position, the oscillation of the lever thus causes them toengage the rack alternately.

The standard 1 is preferably a single casting havin'ga base member 22 and an'up "right member 23; I The .uprightmembe; is

its

. I of substantially U-shaped cross section throughout its length, but has openings 24 in the opposite sides. Inwardly disposed I or removal of the operatingparts isfacilir tated.

- The operation'of the device is as follows When the jack is to be used for raisrack 3.

ing aload,-the lever 17 is shifted to its upperinost position, as shown in Fig. 1, whereby the spring 12 normally urges the pawls 7 and 9 into engagement with the The oscillation of the lever 4 then causes a step by step advance of the member 2, which is raised by the pawl 9 and heldstationary by the pawl 7 when the lever is being operated to secure a new grip by lowering the pawl 9. When it is desired to lower the member 2, the crank 17 is. swung to its lower position, as shown in Fig. 2, which causes the shoulder 16 of the cam member letto urge the spring 12 for-- Ward so as to retract the pawls 7 and 9. As

the pawl 9 is now elevated through the downward-stroke of the lever 4, it coacts,

with the shoulder 20' and is urged forwardly against the'pull of the spring 12 and into engagement with'the rack 3. As

the pawl 9 enters into engagement with the rack '3, the latter is lifted slightly and the pawl 7 is' released from the rack and retracted by the spring 12, permitting the member 2 to be lowered as the lever swings to lower the pawl 9. As-t-he lever swings upward,'its inner end, which forms the cam 21, coacts with the pawl .7 and urges it into engagement with the rack 3, whereupon a further lowering of the pawl 9 frees itfrom the pressure of the load on the rack and allows the spring 12 to retract it. The oscillation of the handle thus causes the member 2 to be lowered-in the standard 1.

3 Although but one specifieembodiment of this invention is herein shown and described,

it will be understood that numerous detailsof the construction shown may be altered or 'omitted without departing from the spirit of this invention, as defined by the followmg claims. v Y Y I claim 1. In a lifting jack, the combination of frame, a rack movable thereon, a pawl pivotally mounted in said frame and adapted for.engagement with said rack, a lever fulcrumed on said frame, a pawl pivotally carried by said lever and adapted for engagement with said rack, a rod connected to said pawls, a flat spring secured to said frame and connected to said rod and adapted to normally urge said pawlsinto engagement with said rack, a member journaled in said frame adjacent to said spring, a shoulder on said member, and means for shifting said member to cause'said shoulder to shift said spring for urmng said pawls out of engagement with said rack.

2. Ina lifting jack,- the combination of a frame, a rack movable thereon, a' pawl onsaid frame adapted for engagement with said rack, a lever fulcru'rned on said frame, a pawl carried by said lever andadapted for engagement with said rack, a rod -connect-' ing said pawls, a flat spring secured to said frame and connectedwith said rod, a shaft journaled in said frame adjacent to said spring and having a recess adaptedto re ceive said'spring topermit said-spring to normally urge said pawls 'into engagement with said rack, and means for turning said shaft and thereby causing it to shift 7 said spring so as to urge said pawls out of engagement with said rack.

3. In a lifting-jack, the combination ofa frame, a rack movable thereon, apawl pivotally mounted in said frame and adapted for engagement with said rack, a lever fulcrumed on saidframe, a pawl pivotally carried by said lever and adapted for engagement with said rack, a rod pivotally connected to one of said pawls and slidingly connected to the ,oth er,'a flat spring secured to said frame and having sliding connection with said rod between said pawls and adapted to normally urge said pawls into engagement with said rack, a member journaled in said frame adjacent'to said spring,

a shoulder on said member, and means' for shifting said member to cause said shoulderoshivft'said spring for urging said pawls out of engagement with'said rack. 1

Signed at Joliet this 27th day of February, 1911. I T ALFRED VANiFLElllT.v Witnesses: v I

HENRYR. POHL, FREDERICK W. Pom. 

